Vesicles from Pluronic L121 (PEO5-PPO68-PEO5) triblock copolymers were stabilized against aggregation by Pluronic P85 (PEO26-PPO40-PEO26) micelles. Both the vesicles and the micelles were reinforced by an interpenetrating polymer network from pentaerythritol tetraacrylate (PETA). AFM, electron microscopy and fluorescence labeling studies are used to investigate the morphology of the capsules. The P85 micelles are integrated into the L121 polymersome walls, while both types of Pluronic block copolymer are also non-covalently trapped in their respective interpenetrating acrylate networks. The micelle-containing vesicles retain their size upon heating until at least 33 °C. Upon cooling below room temperature the vesicles reversibly loseblock copolymers. It was shown that the double-stabilized vesicles are readily internalized in HeLa and Caco-2 cells.